Crushing and grinding machine



Feb. 10, 1942.

J. E. DICK CRUSHING AND GRINDING MACHINE Filed July 29, 1959 5 Sheets-Sheet l Feb. 10, 1942. J, E, DICK 2,272,908

GRUSHING AND' GRINDING MACHINE 3 Sheets-Shem 2 Filed July 29 1959 Z1144. f w: I//// I:-

jnvenior By Jog/150mg,

Feb. '10, 1942. J. E. DICK.

CRUSHING AND GRINDING MACHINE Filed July 29, 1939 '3 Sheets-Sheet 3 Patented Feb. 10, 1942 UNITED STATES CRUSHING AND GRINDING MACHINE John E. Dick, Hallock, Minn.

Application July 29, 1939, Serial No. 287,290

2 Claims. I (O1. 83-8) My present invention relates to crushing or grinding machines which are particularly adapted to use in grinding various kinds of grains for use in the more or less coarse grinding or crushing of various grains and the like.

While the machines of the invention are adapted for a wide variety of uses, they are particularly adapted for grinding grains such as wheat, corn, oats, barley, rye and the like in the manufacture of feed for poulty and stock, and machines built in accordance with this invention and used for this purpose are generally referred to as feed mills.

More specifically stated, the present invention is in the nature of an improvement on or modification of the machine of my prior application S. N. 87,926, filed June 29, 1936, under the title Crushing machine, which became Patent No. 2,172,151 on September 5, 1939.

While the present machine is very similar in design to the machine of the prior application identified, it incorporates an improved means of preventing passage of harmful obstructions such, for example, as stones, nails, bolts, screws and the like from the feed chamber of the machine into the crushing chamber of the machine. In this connection it may be stated that whereas both the machine of this application and that of the prior application are so designed that most foreign substances such as described and which are delivered with the grain into the feed chamber, will become trapped in the bottom of the feed chamber and never permitted to reach the passage to the crushing chamber, it is impossible to make such an arrangement work one hundred percent (100%) and therefor it is necessary or at least highly desirable to further safeguard the grinding mechanism, and while this further protection of the grinding mechanism is quite effectively accomplished by the mechanism illustrated in my earlier application, the mechanism of the present application provides a less expensive, simpler and even more highly efiicient arrangement for accomplishing this last stated purpose.

A further object of the present invention is the provision of a novel mounting for the rotary grinding disc of the machine whereby the rotary grinding disc will automatically maintain itself properly aligned with respect to its cooperating stationary grinding disc.

A still further object of the present invention is the provision in a machine of the kind described embodying a grinding or crushing chamber having rotary and stationary grinding discs therein 56 ATENT OFFICE and in which ground material will be automatically discharged from the crushing chamber at high velocity.

A still further object is the provision of such a machine in which the ground material discharged at high velocity will be discharged in a concentrated stream having a very narrow angle of spread or divergence so that the material can be automatically delivered to a remote and relatively concentrated area quite distant from the machine.

The above noted objects and advantages of the invention will be made more clear and. still further important objects and advantages will become apparent from the following specification and claims.

In the accompanying drawings like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a view showing the machine in end elevation and diagrammatically illustrating the delivery of material therefrom to a remote point;

Fig. 2 is an enlarged perspective View of the machine;

Fig. 3 is a transverse sectional view taken on the line 33 of Fig. 4;

Fig. 4 is an axial sectional View through the machine with some parts on the section line shown in full;

Fig. 5 is a fragmentary detail view; and

Fig. 6 is a detail sectional view with some parts broken away and some parts shown in section taken on the line 6-6 of Fig. 4.

In its preferred embodiment herein illustrated the machine includes a feed chamber 10 that is open at its top and provided with vertical front and rear walls II and I2 respectively. Mounted on the open upper edges of the feed chamber I0 is a receiving hopper l2. In the preferred form of the machine illustrated, the walls and bottom of the feed chamber [0 are integrally cast and there is integrally cast with the rear wall a rearwardly extending U-shaped mounting bracket [3.

Adjacent the front end of the crushing chamber l0 (seen at the left in Fig. 4) is the machines crushing or grinding chamber M which is provided by a two-part grinding casing comprising axially separable front and rear casing sections I5 and 16 respectively. The rear grinding casing section I6 is bolted or otherwise rigidly secured to the front wall H of the crushing chamber as at IT and is provided with an axial intake passage l8 that is aligned with and forms a continuation of the passage formed by an aperture IS in the front wall of the grinding chamber M.

The front and rear sections l5 and [6 of the grinding casing are normally rigidly secured toether by nut equipped bolts 2%. The passage I8 and orifice l9 forming part thereof are preferably located materially above the bottom of the feed chamber lll so as to form below the outlet passage to the grinding chamber a sump for the trapping and accumulation of relatively heavy foreign substances such, for example, as stones, nails, bolts, screws, various metallic elements and the like, which, if passed on from the feed chamber, would be apt to damage the grinding mechanism.

The front section it of the grinding casing is shown as being integrally formed with a forwardly extending tubular portion 2| that is contracted near its outer end to form a bearing supporting sleeve 22 and a stop shoulder 23. Axially slidably working in the reduced diameter bearing sleeve 22 and projecting forwardly materially outwardly thereof and rearwardly into the enlarged tubular portion 2! is a long bearing sleeve 24 that is provided with an annular flange 25 at its inner end. The bearing sleeve 24 preferably fits quite loosely in the sleeve 22 so as to permit slight wobbling action necessary for self-alignment of the bearing sleeve 26.

The rear wall l2 of the feed chamber i6 is provided with an aperture 26 in axial alignment with the passage l8 and bearing sleeve 24. Passed axially through the aperture 25, passage I8, crushing chamber l4 and into the bearing sleeve 24 is a power driven shaft 2'1, which shaft is journaled at its rear end in a bearing 28, preferably of the self-aligning type, which is mounted in the rear or end member of the supporting structure 13. The shaft 21 may be assumed to be axially slidable in the bearing 28 and at its forward end the shaft is journaled in the selfaligning bearing sleeve 24 through the medium of a race of roller bearings 29 which are axially slidable in the sleeve with the shaft.

Mounted on the driven shaft 2? within the crushing chamber M is a rotary grinding disc 38 that is provided with a removable annular grinding plate 3| of more or less conventional character and which is provided on its inner surface with grinding teeth. This grinding plate 3i cooperates with an opposed similar stationary grinding plate 32. The rotary grinding plate 3i is anchored to the rotary grinding disc 30 by nut equipped bolts 33, and the fixed grinding plate 32 is similarly anchored to the rear section l6 of the crushing chamber by nut equipped bolts 36;.

The opposed grinding plates 3! and 32 are oppositely bevelled toward their axes to form an annular intake mouth 35. Th rotary grinding disc 33 is formed with a tubular hub which comprises a forwardly projecting hub flang 36 and a rearwardly projecting hub flange Bl.

As will be seen particularly by reference to Fig. 4, the bore of this hub fits the shaft quite snugly at its intermediate portion but is flared both forwardly and rearwardly from its rather narrow intermediate hub engaging portion so as to permit slight wobbling movements of the rotary grinding discs on the shaft 27.

For-driving the rotary grinding disc 36 from the shaft 21 and for locking the rotary grinding disc against axial movement on the shaft in a forward direction, there is provided a shear pin 33 which is passed transversely through the shaft and has its extended ends seated in forwardly opening radial notches 39 in the end portion of the hub flange 35. Located within the large diameter portion of the tubular extension 2| of the forward grinding casing section I 5 surroundin the bearing sleeve 24, is a coil compression spring 66, one end of which spring is seated against the shoulder 23 and the other end of which is seated against the sleeve flange 25.

The purpose of this spring is to keep the cooperating grinding plates 3i and 32 under desired yielding grinding pressure and for the purpose of varying the yielding pressure exerted by the pring i6 and for completely relieving the rotary grinding disc and plate of pressure, the following described mechanism is provided, to wit: A cylinder 4| having a threaded orifice Z2 is rotatively and axially slidably mounted in the outer end of the tubular bearing sleeve 24. This cylindrical member 4| outward of the end of the bearing sleeve 24 is provided with a projecting operating lever 3. The cylindrical wall of the cylindrical element il is provided within the sleeve 24 with a spiral slot 44.

Working in this slot M is the projected inner end of a stud Q5 that is threaded into the sleeve 2d. Passed axially through the cylinder 4| and having screw threaded engagement with the threaded orifice thereof is a screw threaded shank 15, which, through means of a swiveled head 41 and thrust bearing 48, engages the end portion of shaft 21. The thrust bearing 68, which is shown as being of the anti-friction type, work between the swiveled head ii and a shaft flange 49.

For locking the screw threaded shank 36 in desired position there is provided a lever equipped lock nut 50.

The cylindrical element i normally positioned as illustrated in its innermost position with the stud d5 engaging the outer end of the piral slot 34, but when it is desired to quickly relieve the grinding discs of tension of the spring ill or in other words to back the rotary grinding disc away from its cooperating disc, this can quickly be accomplished by rotating the lever 43 until the opposite end of slot 44 engages the stud '35; this being possible because, as will be evident from the drawings, the spring 48 can only exert grinding pressure on the disc 39 through the sleeve 24, cylinder ll and stem 65. By means of the screw threaded shank t6 the desired grinding conditions may be obtained.

Telesoopically applied over the intermediate portion of the driven shaft 21 and extending substantially from end to end of the feed chamher it and through the passage [8 is a hollow feed screw indicated as an entirety by the numeral 5i. Near its forward end the hollow feed screw is provided with a radial bearing flange 52, the bore of which bears upon the shaft 52 and the forwardly and outwardly diverging or conical front surface of which engages a correspondingly bevelled conical rear end of the rotary grinding disc flange 37. The forward end of the feed screw El is also formed with a forwardly projecting annular flange 53 that works telescopically over the flan e 31 but with considerable clearance so that it will not interfere with the relative wobbling action of the grinding disc 30.

The rear end of the hollow feed screw 5| is integrally formed to afford a rearwardly diverging clutch flange 54 having an internal conical clutch surface 55 for cooperation with an external conical clutch surface 55 formed on the forwardly diverging front end of a drive sleeve 56. The sleeve 56 is mounted on the shaft 21 through an internal radial flange 51 and is driven with the shaft through a Woodruff key 58 seated in the shaft and working in a slot in the flange 51. The key slot just referred to extends entirely through the flange 51 axially thereof so that the sleeve 56 is free to move axially onthe shaft 21.

Also telescopically applied on the shaft 21 is a relatively light coil spring 59 which presses against the sleeve flange 51 at its forward end and at its rear end reacts against an axially adjustable collar 69. This spring, being relatively much lighter than the spring 40 does not materially affect the adjustment of the grinding disc spring 40 but does serve to urge the sleeve 56 forwardly with sufiicient pressure to keep the cooperating friction clutch surface of the screw and sleeve in tight enough frictional engagement to furnish grinding energy for grinding light material such, for instance, as wheat, oats and other small grains.

The tension of spring 59 also serves to keep the driving notches 39 tightly engaged over the shear pin 38, which shear pin serves as a final base of reaction in a forward direction.

A pulley 6| is provided on the rear end portion of the shaft for the purpose of driving the shaft 21 through a belt not shown through a suitable source of power such as an electric motor or gasoline engine, not shown. This pulley 6| is looked to the shaft 2'! by a lock bolt 62.

Preferably and as herein illustrated, the hollow feed screw 5! diverges from its rear toward its forward end. Also, in its preferred form illustrated, it will be noted that the angle of divergence is substantially continuous'from its rear end to approximately the point where the feed screw enters the passage 18, and from this point on, the angle of divergence is increased, preferably continuously increased. Also important to note in connection with Figs. 4 and 5 is that the feed screw passage i8 is forwardly diverging to correspond to the divergence of that portion of the feed screw within the same, and that the minimum diameter portions of the passage [8 are spaced from the maximum diameter portions of the feed screw therein only sufficiently to provide free working clearance.

Particularly by reference to Figs. 4, 5 and 6 it will be seen that the walls of the passage l8 are cut out or otherwise formed to provide circumferentially spaced spiral teeth 53 and inter vening notches t l. Each of these spiral teeth is pitched from its base immediately adjacent an adjacent tooth to its apex or crown, and the ends of the teeth facing opposite the direction of rotation of the feed screw are radially disposed with respect to the feed screw. The maximum diameters of the passage l8 are taken by measuring between the crown or apex of diametrically adjacent teeth; whereas, the minimum diameters of the passage l8 are arrived at by measuring between the base portion of diametrically opposed teeth 63.

The feed screw 27 is formed on its periphery with a plurality of spiral threads illustrated as being three in number and indicated by 'a, b and 0. According to the example given, the thread 11 extends from front clear to the rear end of the screw; whereas, the threads h and c terminate somewhat short of the end of the feed screw. The several threads at, b and 0 each taper rearwardly substantially to the rearwardly adjacent thread and are of gradually diminishing depth from rear toward the front end of the screw.

Located in the upper portion of the feed chamber Ill above the feed screw is a partition structure comprising a rigid fixed partition section 55 and a movable gate-acting partition section 66. The partition section extends between the opposite sides of the chamber In and from the front wall thereof to the longitudinally intermediate portion of the feed chamber, and is suitably anchored to the sides and front of the said feed chamber.

The gate acting partition section 66 is'rnounted for sliding movements longitudinally of the feed chamber from the forward position shown in Fig. 4 to a rearward position wherein it will substantially close the intake passage between the hopper l2 and the feed chamber.

For the purpose of readily shifting the gate 86 there is provided a push rod 61. The grinding or crushing chamber casing is formed with a tangentially disposed laterally and upwardly inclined discharge neck 58 detachably applied to which is a concentrating and directing spout indicated as an entirety by 69. This spout which is rectangular at its base portion and vertically elongated to correspond to the shape of the outlet neck 58, is somewhat contracted toward its end and at its free end is preferably of cross sectionally cylindrical contour.

This spout, which constitutes an important phase of the instant invention, is open at its bottom throughout most of its length. The rear base end portion of the spout is primarily wide open as at 10; whereas the opening in the forward portion is reduced to form a relatively narrow slot 7|. H! of the spout is partially closed by a bafile structure l2, the longitudinally intermediate portion of which is equipped with anchoring flanges 13 that are suitably and securely anchored to the open lower edges of the spout, and an inwardly prcjecting baffle tongue M and a forwardly projecting baffie tongue 15.

The inwardly projecting baffle M is turned downwardly with respect to the axis of the spout; whereas, the baflie 15 is turned upwardly with respect to the axis of the spout.

In Fig. 4 the cooperating clutch surfaces of the feed screw 5| and sleeve 56 are shown as positively locked together for common rotation by a shear pin 15 in the nature of a machine screw. However, it should be understood that this shear pin-acting screw 16 which is screw threaded through the flange 54 of the screw and works in a slot-like aperture H in the conical portion of the sleeve 56, is preferably employed only for grinding relatively coarse and heavy materials such, for example, as corn and will usually not be employed in the grinding of small grains such as wheat, oats, rye and the like.

Operation The operation of the machine in connection with small grains such as wheat, rye, etc. will first be given, and hence it may be assumed that shear pin 16 has been removed so that the feed screw is driven slowly by virtue of frictional engagement between the cooperating conical clutch surfaces. It may further be assumed that the machine is being driven from a suitable source of power through the pulley 6 l The material to be ground is, of course, shoveled or otherwise conveyed to the hopper 12 from which it will flow under gravity into the feed This initially open bottom portion chamber ID at the rate controlled by the positioning of the gate 66, and, of course, the flow into the feed chamber ID will be confined to the rear end portion thereof. Under rotation of the shaft 21, the feed screw Will, of course, be driven by virtue of the frictional engagement between the cooperating clutch surfaces and the rotary grinding disc 30 will be driven also at shaft speed through the driving shear pin 38.

The feed chamber ID will usually be maintained full or at least to a level above the feed screw, and the grain engaged by the threads of the screw will be moved spirally forwardly and through the passage l8 into the axial portion of the feed chamber 14 inwardly of the grinding plates 3| and 32. From this point the whole grain will pass radially outwardly between the cooperating grinding plates 3| and 32 which will crush and grind the same to a varying extent determined largely by the yielding pressure exerted by the spring 40 on the rotary grinding disc and plate.

The ground material will be discharged from the space between the cooperating rotary and non-rotary grinding plates 3| and 32 at high velocity and substantially tangentially of the rotary grinding disc into the cylindrical inner peripheral portion of the crushing chamber. In this connection it will, of course, be understood that the material in passing between the rotary The ground feed thus discharged into the peripheral portion of the grinding chamber will be discharged therefrom at high velocity through the tangentially disposed discharge neck 68 into the spout 69. Upon passing into the spout 69 some of the ground material will be directed toward the closed top thereof or directed quite straight axially thereof, but other portions of the ground material will be directed toward the bottom of the spout and would, in the absence of the deflectors M and 15, pass angularly through the open bottom of the spout. However, some of these downwardly diverted grindings will strike the deflector M and be deflected back into the high velocity concentrated portion of the stream and grindings that are downwardly diverted at a lesser angle will strike the inclined deflector l5 and be deflected back into the more concentrated portion of the stream. Hence, it will be evident that such grindings as tend to become downwardly diverted and separated from the concentrated main stream are, by the defiectors 14 and I5, diverted back into the concentrated stream and will be carried with the concentrated portion of the stream.

In the use of most machines of this general character the grindings are discharged at relatively low velocity and are permitted to pile up close to the discharge from the grinding chamber from which point they are usually conveyed by shoveling or other means to a remote storage point. With this machine, however, the grindings are discharged at such high velocity and are in such a concentrated well directed stream that merely by directing the discharge spout the grindings may be automatically delivered to the desired'remote storage point. An example of this is shown in Fig. 1 wherein X indicates the fioor of a building, Y indicates a wall of a storage space and Z indicates an opening through which the stream of grindings is directed. In Fig. 1 the pile of grindings is indicated by D.

In practice it has been found that a spout having a closed bottom and being devoid of defiectors herein illustrated does not, in the first place, provide as concentrated a stream of grindings as does the spout illustrated and described; and, in the second place, such a closed bottom spout plugs very rapidly when the moisture content of the grindings is high. Whereas, the spout described incorporating an open bottom and the deflectors does not become plugged even when operating with wetgrindings as the open bottom does give wet grindings, which lose velocity and tend to plug the spout, an opportunity to drop out by gravity so as to clear the interior of the spout of such obstructions and permit continued operation.

In such a case, of course, there will be some grindings discharged beneath the spout but this will represent a small percentage of the total and may readily be shoveled up.

Heavy particles of foreign substance such for example as nails, screws, bolts and the like which are fed into the feed chamber along with the whole grain, will usually gravitate to a level below the feed screw and passage l8 during the forward passage of the whole grain from the rear toward the front of the feed chamber, and, of course, these foreign elements will become permanently trapped in the lower portion of the feed chamber from which they may be periodically removed.

In this connection it is, of course, important that the passage l8 and feed screw 51 be well spaced from both the bottom and sides of the feed chamber and that the feed be delivered to the chamber I0 toward the rear end thereof. Although this arrangement, which is common to that of my prior application, has be n found very effective in eliminating or trapping damaging obstructions before they have an opportunity to obstruct or damage the mechanism, there are bound to be occasions when such a foreign element may find its way to the passage l8. However, in view of the shape of the feed screw within the passage, the shape of the passage !8 and the cooperative relation between the walls of the passage 18 and the feed screw, most foreign substances large enough and of such nature to cause damage to the grinding discs, should they be passed therebetween, will become jammed between the feed screw and the toothed walls of the passage I8 which will cause the feed screw to stop, therebetween the cooperating clutch surfaces of the rear end of th feed screw and the front end of the sleeve 55 will slip and permit continued operation of the pulley 5!, shaft 21 and rotary grinding disc til.

Here it may be stated that the driving tension exerted by the spring 59 on the cooperating clutch surfaces will preferably be just suflicient to afford continuous operation of the feed screw at shaft speed when feeding small grains such as described so that the feed screw will stop and slip under jamming of even relatively light for eign material.

For the grinding of heavy material such as corn, it is necessary either to quite greatly in crease the driving tension exerted between the cooperating clutch surface and spring 59 or to utilize th shear pin 18 in addition to the friction clutch tension. This shear pin 16 will preferably have just sufiicient shearing strength to provide the necessary driving energy for this heavy material and to shear under an abnormally heavy load such as would be produced by jamming between the feed screw and the walls of the passage 33 of foreign substances such as stones, bolts, nails and the like.

The very small clearance maintained between the feed screw and the minimum diameter portions of the walls of passage [8 and the increasing angle of divergence of the feed screw and passage is within the passage it results in greatly increasing the eificiency of the device in catching foreign obstructions such as described before they are permitted to enter the feed chamber.

It will be understood that a nail, for example, which had a diameter less than the clearance between the feed screw and the minimum diameter portions of the walls of the passage is and g which would pass freely through to the crushing chamber were the walls of the passage and feed screw within the passage of constant divergence providing the nail was longitudinally disposed,

would become jammed between the feed screw and the walls of the passage in the present machine due to the changing angle of divergence of the cooperating portions of the feed screw and passage. In other words, in the present machine, a straight nail, for example, in order to enter the crushing chamber would have to pass through a curved passage which would require bending of the same and which would result in jamming, and this, regardless of whether the nail was transversely or longitudinally disposed.

Of course, it will be understood that foreign substances which jam the feed screw in the passage IB must be removed before operation of the machine can be continued and that it will be necessary to stop the motor driven shaft for such removal operation.

The feed screw in this machin is capable of delivering material to the feed chamber at a greater rate than the grinding discs are capable of handling the feed, so that in operation the whole grain will be jammed tightly into the annular space surrounding the shaft 2? within the annular grinding plates 3| and 32, and this action serves to more or less crush the grain prior to its being passed between the grinding plates. This feature is important for the reason that it permits of the grinding plates being operated under less pressure from the spring M3 for any given grinding, which, in turn, results in longer life to the grinding discs. In fact, for most purposes, the grinding discs will scrape only slightly when the machine is initially started and before it gains full speed, and as soon as the machine gains full speed there would be enough inrush of air through the discs to largely prevent their scraping or at least their scraping to a detrimental extent. The above statement is made with the presumption that the machine is starting with the material in the grinding chamber [9. When the machine is operating at full speed and the grinding chamber is filled with material, the material will be packed so tightly into the passage 18 by the feed screw that the inflow of air will be substantially choked off. In this machine the material is discharged at high velocity by virtue of the force with which it is thrown centrifugally from the space between the grinding discs since there is practically no air movement through the grinding chamber under continuous operation of the machine.

The forward side Wall of the grinding chamber is preferably provided with'small ports 'I'l which are provided only for the purpose of keeping dust away from the shaft bearing, but it is found that in service there is very little movement of air through these ports and that the machine will actually operate as well without ports.

Preferably the rotary grinding disc 30 is provided at its periphery with a circumferentially spaced series of impelling lugs 30 which, while not essential, do nevertheless materially increase the efficiency of the device insofar as its automatic centrifugal discharge of ground feed or material is concerned.

As will be seen particularly by Figs. 2 and 3, the deflectors I4 and 15 are located in successively higher points or planes within the spout with respect to the transverse center of the spout. In fact, in the preferred arrangement illustrated it will be noted that the baffle '14 is located almost Wholly below the open bottom of the spout, whereas the forwardly inclined baffle 15 is located almost wholly above the bottom of the spout. This is important in that the ballles 14 and I5 intercept material having different degrees of divergence from a straight line axial of the spout. Also it is important to note that the baflies l4 and I5 extend transversely from side to side of the spout and are formed of ductile matter such as sheet iron which can be bent to provide different degrees of inclination in order to arrive at the highest degree of efiiciency by experimentation with various different kinds and conditions of material.

Not only do the teeth 63 very materially increase the efficiency of the device in catching hard foreign substance such as might cause damage to the grinding mechanism, but also they increase the capacity of feed of the machine for any given minimum clearance between the passage l8 and the feed screw. In practice it has been found that the machine is more efiicient in catching foreign substance with the teeth as illustrated than with out the same even though the minimum clearance between the feed screw and passage 18 be maintained approximately equal to the present clearance. of course, this last condition would be practical since it would greatly reduce the handling ability of the feed mechanism.

What I claim is:

1. In a device of the class described, a grinding casing having an inlet pas-sage and a tangential outlet passage, cooperating rotary and non-rotary annular grinding plates in said casing, means for delivering material to be ground to the radial inner portions of said grinding plates, wherefrom the material will take an outwardly spiral course through the space between the grinding plates and will be discharged substantially tangentially therefrom at high velocity in a ground condition, and a spout forming a continuation of said tangential outlet passage and disposed with its axis substantially tangent to the peripheral discharge through said outlet passage, said spout being provided at its intermediate portion and closely adjacent the bottom thereof with a longitudinally spaced plurality of bafiles that are forwardly inclined with respect to the axis of the spout, and said spout being open at its bottom both forwardly and rearwardly of said bafiles, said baiiles extending transversely across and closing the intermediate bottom portion of the spout.

2. In a device of the class described, a grinding casing having an inlet passage and a tangential outlet passage, cooperatingrotary and non-rotary annular grinding plates in said casing, means for delivering material to be ground to the radial inner portions of said grinding plates, wherefrom the material will take an outwardly spiral course through the space between the grinding plates and will be discharged substantially tangentially therefrom at high velocity in a ground condition, and a spout forming a continuation of said tangential outlet passage and disposed with its axis substantially tangent to the peripheral discharge through said outlet passage, said spout being provided at its intermediate portion and closely adjacent the bottom thereof with a longitudinally spaced plurality of bafiles that are forwardly inclined with respect to the axis of the spout, and said spout being open at its bottom both forwardly and rearwardly of said bafiles, said bafiles extending transversely across and closing the intermediate bottom portion of the spout, the first in line of said bafiles extending below the bottom of the spout and the second in line thereof being located above the bottom of the spout.

JOHN E. DICK. 

